Locking mechanism for the tool holder of a planing machine



United States Patent O" 9 6 Claims. (Cl. 90-55) The present invention relates to a mechanism for locking the tool holder of a planing machine.

In modern planing machines, especially those with a high cutting power, the planing tool is no longer permitted to slide over the workpiece during the return stroke but it is positively lifted by reciprocating means off the workpiece and then moved by these means again into the cutting position before the next cutting stroke. This may be done by two different methods, namely, by pivoting the tool holder so far that the planing tool is spaced from the workpiece or by moving the tool holder in a straight direction within a guideway. The present invention relates to a tool holder of the last-mentioned type which is slidable back and forth in a straight direction.

When starting each individual cut and also during the actual cutting, especially when making cuts of a great depth, there is considerable danger that the planing tool will start to vibrate and chatter. This requires the tool holder to be locked relative to its guideway after the planing tool has been moved to its cutting position. There are already a series of prior proposals for achieving this purpose. According to all of these proposals, the locking effect is produced by clamping the tool holder in a fixed position relative to the tool holder guide by means of cam or wedge surfaces, that is, by a frictional locking action..

It is an object of the present invention to provide a new method of locking the tool holder to the guideway thereof by positive locking means in the form of a boltlike member rather than by frictional locking means. This not only permits a much more simple and inexpensive construction, but it also avoids the need for adjustments which occurs from time to time because of the wear upon the cam or wedge surfaces of such locking means.

A feature of the invention for attaining the abovementioned object consists in providing the positive locking means in the form of a simple crossbolt which is movable by the control rod of the tool holder and engages into a locking recess in the guideway of the tool holder.

There are various possibilities of translating the longitudinal movement of the control rod of the tool holder so as to attain a transverse movement of the locking bolt. An especially advantageous possibility consists in providing the crossbolt with a pair of rollers which is operatively associated with a pair of corresponding cam surfaces on the control rod.

According to another embodiment of the invention which will be subsequently described in greater detail, the control rod is connected to the tool holder by spring means, preferably in th form of a set of cup springs. These spring means may be designed and arranged so as to press the tool holder when in the raised position into engagement with a fixed upper stop member.

' The above-mentioned as well as additional features and advantages of the present invention will become more clearly apparent from the following detailed description thereof which is to be read with reference to the accompanying drawing which shows a longitudinal section of a preferred embodiment of the invention;

In this drawing, the numeral 1 indicates the slide carriage of a planing machine, 2 the tool holder, 3 the guideway of the tool holder which is secured by screws 4 to the 3,262,371 Patented July 26, 1966 "ice slide carriage 1 and also carries a pneumatic or hydraulic drive mechanism 5. This drive mechanism 5 consists in a conventional manner of a cylinder 6 and a piston 7 which is slidable therein and the piston rod 8 of which serves as a control rod for adjusting the position of the tool holder 2. This control rod 8 is not rigidly connected to the tool holder 2 but acts thereon through a set of cup springs 9. The numeral 10 indicates a lower stop member on the tool holder 2 which is associated with a fixed stop member 18 on the guideway 3 of the tool holder. The numeral 11 indicates an upper stop member on the tool holder 2 Which is resiliently mounted thereon by a spring 12 so as to act as a shock absorber when engaging with a fixed stop member 13 which may be adjusted to the desired elevation of the tool holder 2 by a racklike device 14.

When the planing machine is not in operation, the lower end 15 of the control rod 8 is located at a certain distance from the bottom 16 of a bore in the lower end of the tool holder 2.

In order to understand the invention more clearly, it may be advisable first to explain roughly the mode of operation of the means as above described.

In order to move the tool holder 2 to the cutting position, a pressure medium, for example, compressed air or oil under pressure is passed through the bore 17 into the chamber above the piston 7 which then moves downwardly and thereby takes along the control rod 8. Since the set of cup springs 9 is very stiff, the movement of rod 8 is transmitted via the spring 9 to the tool holder 2 and the latter is there-by moved downwardly until its stop member 10 abuts against the stop member 18. The tool holder 2 is then in its cutting position. Rod 8 can, however, continue to move downwardly since it is not rigidly connected to the tool holder, and it thereby compresses the spring 9. The stop members 16) and 18 are therefore clamped together in accordance with th pressure of spring 9.

In order to lift the tool holder 2, the pressure medium is injected into cylinder 6 so as to act upon the lower side of piston 7. Spring 9 is thereby released, the stop member 10 disengages from the stop member 18, and the tool holder 2 is lifted until its stop member 11 engages upon the fixed stop member 13 and thereby compresses the spring 12. The tool holder has then again reached its upper position.

It has already been mentioned above that, due to the further movement of rod 8 after stop member 10 first engages with the stop member 11 and due to the'resulting compression of the set of cup springs 9, the two stop members 10 and 18 are clamped together so that the tool holder 2 is also locked in a fixed position relative to the guideway 3. found that this locking .action is not sufiiciently secure and that therefore additional locking means are required. According to the present invention these locking means are of a positive locking type and essentially consist of a bolt 19 which is movable in a direction transverse to the axis of the control rod 8 along guide surfaces 20 within the tool holder 2. This bolt 19 is operatively associated with a locking recess 21in the guideway 3 of the tool holder. As soon as the tool holder 2 during its movement to the cutting position as above described reaches its lowest position, bolt 19 is shifted toward the right and into the locking recess 21 in the guideway 3. The tool holder 2 is then positively and securely locked to the guideway 3, and this locking action does not require any clamping surfaces which have to be accuratelyfitted to each other and which are due to become worn. Before the tool holder is lifted, bolt 19 is again retracted and thereby permits the control rod 8 to move upwardly.

In order to effect a positive movement of bolt 19, it is necessary to translate the longitudinal movement of rod In actual practice it has, however, been the invention, this is attained in a very simple and reliable manner by providing the bolt 19 with a pair of rollers 22 and 23 which engage with a pair of cam surfaces 24 and 25 on the control rod 8. When this rod 8 moves downwardly from the position as illustrated in the drawing, there will at first be no relative movement between the rollers 22, 23 and the cam surfaces 24, 25 since rod 8 at first also does not mov relative to the tool holder 2. However, as soon as the downward movement of the tool holder 2 is stopped by the engagement of the stop members 10 and 18 and rod 8 then continues to move downwardly against the action of spring 2 so that a relative movement occurs between rod 8 and th tool holder 2, the cam surface 25 acts upon the roller 23 and the force exerted by it results in a component which is directed transversely to the axis of rod 8 and therefore acts transversely upon the bolt 19 Which is thereby shifted to the right and into the locking recess 21. When at the end of the cutting stroke the tool holder 2 is lifted to disengage the planing tool from the workpiece during the return stroke, the other cam surface 24 comes into action by exerting through the roller 22 a transverse force upon the bolt 19 toward the left and it thereby retracts the bolt from the locking recess 21. Piston 7 is then free to move the tool holder 2 to its upper position until the stop members 11 and 13 engage with each other.

Although my invention has been illustrated and described with reference to the preferred embodiment thereof, I wish to have it understood that it is in no way limited to the details of such embodiment, but is capable of numerous modifications within the scope of the appended claims.

Having thus fully disclosed my invention, what I claim 1. A mechanism for locking the tool holder of a planing machine during the cutting stroke thereof comprising a guideway, a toolholder slidable longitudinally along said guideway, said guideway having a locking recess, a boltlike element slidable in said toolholder in a direction transverse to the direction of movement of said toolholder and adapted to engage into said locking recess when said toolholder is in its cutting position, and means for moving said tool holder from a retracted position to a cutting position and for also moving said boltlike element into said locking recess when said tool holder is in said cutting position.

2. A locking mechanism as defined in claim 1, further comprising a stop member on said guideway for 'determining the cutting position of said tool holder, said means for moving said tool holder and said boltlike element comprising driving means, a control rod connected to and adapted to be reciprocated by said driving means, and connecting means for connecting said control rod to said tool holder in a manner so that during the movement of said control rod by said driving means in one direction, said tool holder is moved from a retracted position to said cutting position in engagement with said stop member,

and operatively associated means on said control rod and on said boltlike element for InO-Ving said boltlike member transversely to said direction into said locking recess during a further limited movement of said control rod in said direction while said tool holder is stopped in said cutting position.

3. A locking mechanism as defined in claim 2, in which said operatively associated means comprise a pair of rollers rotatably mounted on said boltlike element and a pair of cam surfaces on said control rod engaging with and adapted to act upon said rollers to shift said boltlike element transversely to said direction during any movement of said control rod relative to said tool holder.

4. A locking mechanism as defined in claim 2, in which said connecting means comprise spring means connecting said control rod to said tool holder so that when said tool holder is moved to said cutting position and is stopped in said position by said stop member, said spring means are compressed during said further limited movement of said control rod, whereby said tool holder is clamped upon said stop member with a pressure equal to the force exerted by said compressed spring means.

5. A locking mechanism as defined in claim 2, in which said connecting means comprise spring means connecting said control rod to said tool holder, said operatively associated means comprising a pair of rollers rotatably mounted on said boltlike element and a pair of cam surfaces on said control rod engaging with and adapted to act upon said rollers to shift said boltlike element transversely to said direction during any movement of said control rod relative to said tool holder, whereby when said tool holder is moved to said cutting position and is stopped in said position by said stop member, said further limited movement of said control rod produces substantially simultaneously a movement of said boltlike element into said locking recess and a compression of said spring means whereby said tool holder is clamped upon said stop member with a pressure equal to the pressure exerted by said compressed spring means.

6. A locking mechanism as defined in claim 2, further comprising a second stop member on said guideway for determining said retracted position of said tool holder, said spring means being adapted to maintain said tool holder in engagement with said second stop member when said tool holder is unlocked and retracted.

References Cited by the Examiner UNITED STATES PATENTS 3,152,514 10/1964 Olson -55 FOREIGN PATENTS 790,717 2/1958 Great Britain.

WILLIAM W. DYER, JR., Primary Examiner. L. VLACHOS, Assistant Examiner. 

1. A MECHANISM FOR LOCKING THE TOOL HOLDER OF A PLANING MACHINE DURING THE CUTTING STROKE THEREOF COMPRISING A GUIDEWAY, A TOOLHOLDER SLIDABLE LONGITUDINALLY ALONG SAID GUIDEWAY, SAID GUIDEWAY HAVING A LOCKING RECESS, A BOLTLIKE ELEMENT SLIDABLE IN SAID TOOLHOLDER IN A DIRECTION TRANSVERSE TO THE DIRECTION OF MOVEMENT OF SAID TOOLHOLDER AND ADAPTED TO ENGAGE INTO SAID LOCKING RECESS WHEN SAID TOOLHOLDER IS IN ITS CUTTING POSITION, AND MEANS FOR MOVING SAID TOOL HOLDER FROM A RETRACTED POSITION TO A CUTTING POSITION AND FOR ALSO MOVING SAID BOLTLIKE ELEMENT INTO 